Capital of Argentina, first founded, 1536, and depopulated, 1541, when the governor transferred the population to Asunción; re-founded, 1580, by Juan de Garay, and called Santisima Trinidad, from Trinity Sunday, the day upon which he landed.
Within the year he built a church, and when the city was transferred from the jurisdiction of Paraguay and made an episcopal see, 1620, this church was dedicated as the cathedral, 1622.
Upon the site stands the new cathedral, built 1791, and modeled upon the Madeleine of Paris.
The Franciscans were already established in the country before the foundation of the city, and there is evidence that the church and convent of Mercy in charge of the Fathers of Mercy until 1821, were standing when Garay founded the hospital of Saint Martin, in the neighborhood.
The present church of the Franciscans dates from 1731; their library of 7,000 volumes is open to the public.
The Jesuits, pioneers in educational work in Buenos Aires, brought architects from Europe to erect the church of Saint Ignatius, 1722, and resided here until their expulsion, 1767; returning later, they built the church of the Saviour, 1872, and now conduct a college in connection with it.
Other notable buildings are the Dominican church and the chapels of Mount Carmel and of the Passionists.
In 1855 the city was raised to an archiepiscopal see.
The Catholic University was founded in 1910, and in 1915 the seminary was authorized to confer degrees in philosophy and theology.
A national Eucharistic Congress was held here, 1916.
New Catholic Dictionary